Electric furnace



T. B. BECHTEL ELECTRIC FURNACE 4 Sheets-Sheet 1 Filed Dec. 12, 1922 T.B. BECHTEL ELECTRIC FURNACE Filed Dec. 12, 1922 4 Sheets-Sheet 2 Dec.1924- 1,517,938

1'. a. BECHTEL ELECTRIC FURNACE Filed Dec. 12, 1922 4 smu -5mm a 1922 4Sheets-Sheet 4 iled'Dc iii in Philadelphia,

Patented Dec. 2, 1924.

UNIT-so sures PATENT OFFICE. I

THEODORE n. macn'rnn,

or'rmnannnrnm, "rnimsrLvAinn, assume]; we r. .1.

RYAN a comm, or PHILADELPHIA, rnnnsvnvnma, a fconrona'rron or zonnawnnnELECTRIC rumvacn Application filed December 12, 1922. SerialN0.-806,3B5.1

3T0 all whom it may, concern:

Be it known that I, THEODORE B. Bronrn a citizen of the United States,residing Pennsylvania, have invented an Electric Furnace, of which thefollowing isa specification.

This invention relates to electric furnaces of'the resistor type and oneof its ob ects 1S to provide such a furnace with novel means rangementand the resistors due to expansion or contraction,

particularly with a view to preventing sagging of said resistors.

It is also desired to provide anovel built structure for supportingthe's'everal sets electric conductors constituting the resistors of anelectric furnace, which structure shall be formed of a minimum number ofdifferent parts designed toc'arry the resistor conductors independentlyof the adjacent walls of the furnace.

Another object of my invention is to lessen the losses of h'eatbyconduction by supporting. the resistors away" from andindependently ofthe furnace walls and to provide a construction which permitsrearrangement of the resistor and its spacing after the furnacestructure has been completed, in order to obtain. any desired relationof the resistors and the objects to be heated.

I also desire to provide an electric furnace in which any of theresistors may beremoved or replaced when desired without affecting thefurnace structure. 1

These objects and other advantageous ends I attain as once being had tothe accompanyingdrawings, in which, g

ig. 1 is aplan ofa furnace constructed in accordance with my invention;i

Fig. 2 is a vertical section on the line 2-2,

Fig.1; a

ig. is a. horizontal section on the line 33,F1g.2; v I

i number of hereinafter set forth, refer- "or sections of an and 5 arerespectively a side and an end elevation of one of theresistor elementswith-its associated supporting structure; 1 v 6 is aoentral verticalsection illustrating a modified form; of'my invention;

and

Fig. 7 is a fragmentary vertical section on the line 7--7, Fig. 6.

In the above drawings, 1 represents a shell or casing-enclosing thebottom 2 and side walls 3 of a vertical type of furnace. Mountedon the]top or otherwiseopen end of this structure is .a cover or closure 4 andthe walls and botliem of the, furnace have their inner facescovered witha refractory lining 50f any suitable material. Mounted on and carriedwholly by the bottom or floor of the furnace is a supporting frameconsisting in the present instance of a number of vertically extendingseries of posts or columns 6 of highly refractory material such asporcelain, lava or the like, although it is to be noted that withoutdeparting from my invention these columns maybe of metal of asufficiently refractory nature when the furnace is designed to operateat relatively low temperatures. i I a The lower ones of these columnsrest directly on the floor and each has interposed between it. andthecolumn next above it a cross fitting. 7 having upwardly opening orrecessed arms for the reception .of the end portions of horizontallyextending support ing bars 8. The .columns ,6, as shown in Figs. 2, 3and 5 may consist of any desired sections 6 and .6 and they arepreferably made tubular for the greater part of their length, being eachprovlded at one 'endwith a projection or dowel-like portion '9 designedto. fit into the lower end of the tubularcavity of the-next highersection or cross fitting.

Thebars 8, shown diagrammatically in Figs. 1 and 3 as elongatedcylindrical rolls of insulating material, are preferably each formedwith or consist of a series of grooved collars,or annular ribs .10designed to define grooves for the reception of the convolutionselectrical conductor 11. Said conductoris thus suspended from the bars 8and is arranged in the form of a series of flat similar loops orconvolutions whose lower ends areengagedand spaced by a secadjacent thevertical face of the refractory lining 5, being arranged, in the caseillustrated, to outline a hexagonal prismatic chamber having three ofthe resistor coils 11 arranged vertically over each other adjacent eachof its vertical sides or faces. The distance between the top and bottombars 8 and 12 of vertically adjacent resistors is such that the adjacentresistors are maintained at the proper distance apart.

Refractory insulating tubes 13-13 are mounted to extend through thefurnace ca'sing, wall and lining to lead the necessary supply conductorsto the ends of the several resistor coils or conductors and underconditions of operation an object to be heated is placed within thechamber defined by the various resistors, the cover 4 being temporarilyremoved for this purpose. After said cover has been replaced, currentdelivered to theresistor coils heats these so as to raise to, andmaintain the furnace and the articles therein at the desiredtemperature.

It is noted that with the above described arrangement of carrying frame,the resistors are supported so as to be altogether independent of theside walls and lining of the furnace, sin e said frame rests upon and iscarried solely by the bottom or floor of the furnace. In that form of myinvention shown in Figs. 6 and 7 I-have shown the casing structure orsetting 1 as carried by a series of supports .14 mounted upon thefoundation members 15, the furnace proper 3 having in the presentinstance an arched top 3". Mounted within said casing and in thisinstance in addition to vertically extending resistor elements 11, areflat coil elements 11 mounted to lie in a plane substantially parallelwith and immediately adjacent the floor. I also provide top ,resistorelements 11 in the form of flat coils mounted immediately adjacent thetop of the furnace.

As in the former case, the vertically extending resistor elements 11 arecarried by vertically extending posts or columns 6 havingprojection-and-recess connections and carrying at their upper ends crossor other fittings 7 and '7", designed to support horizontally extendingbars 8 of insulating material. The conductors constituting the resistorsas before are arranged in flat coils hung from these bars and carryingin their lower portions other bars12. In this case fittings 7' aremounted under each vertical series of columns 6" and are formed withrecessed arms for the reception of cross bars 20 designed to cooperatewith other suitably supported cross bars 21 to carry the horizontal orbottom resistor coils 11". The fittings 7" are designed to carry sets ofcolumns 22, 22 and 23, arranged in arch form across the top of thecasing and serving to support horizontally extending bars 24 and 25, onwhich are carried the top resistor elements 11.

As before the. insulatin tubes 13 are provided at suitable points 0 thefurnace structure for the reception of the conductors through whichcurrent is supplied to the various resistors, sothat under conditions ofoperation I an. object properly supported within the heating chamber ofthe furnace is surrounded by the electrically heated resistor elements.In this case as in that previously described, these elements are carriedupon insulating or metallic frame structuresv of simple form, easy tobuild up or assemble and altogether independent of the side or top wallsof the furnace structure to which they are adjacent. In the event of thebreakage of any of the frame members or of injury to any of theresistors. it may be easily and uickly replaced without dismantling thernace and with but little disturbance to the remainder of the frame orresistors.

While I have shown the resistors as made up of metallic bars, rods orwires. it is to be understood that without de arting from my inventionany other suitable electrical conductors may be used in whatever formmay be required. For example, properl formed resistors containing ormade of carbon may be substituted for the metallic coils shown.

I claim:

1. The combination in an electric furnace of a supporting frameincluding horizontally extending bars; resistor conductors respectivelyhung in coils from said bars; with auxiliary bars hung in said coils andfree to move as the coils expand or contract. said auxiliary bars beingmounted independently of said supporting frame.

2. The combination in an electric furnace of a casing; a supportingframe of insulating material mounted adjacent "but structurallyindependent of the side walls of said casing and including horizontallyextending bars; resistors hung in coils from said bars respectively; andauxiliary bars mounted in the lower parts of said coils respectively.said auxiliary bars being mounted independently of said supportingframe.

3..The combination in an electric furnace of a casing; a frame withinthe casing carried solely by the floor thereof independently of the sidewalls; and resistor elements so m unted on said irame ja nt said sidewalls as to form dependin coils.

4. The combination in an electric urnace of a casing; a supporting framewithin the casing comprising sets of columns and interconnectingsu'pportin elements; and re sistor elements mounte on saidinterconnectin elements.

5. 'Ifiie combination in an electric furnace of a casing; sets ofcolumns of insulating material mounted on the floor of said casing;horizontal bars extending between adjacent columns; and resistorelements hung from said bars.

6. The combination in an electric furnace of a casing; sets of columnsmounted on the floor of said casing; cross fittings associated with thecolumns; bars extending between adjacent cross fittings; and resistorelements carried by said bars.

7. The combination in an electric furnace of a casing; sets of columnsmounted on the floor of said casing; fittings carried by the columns andhaving upwardly openin recesses; bars mounted in the recesses 0 adjacentfittings; and resistor elements carried by said bars.

8. The combination in an electric furnace of a casing; sets ofinsulating columns mounted on the floor of said casing; fittings carriedby the columns and having upwardly opening recesses; bars mounted in therecesses of adjacent fittings; and resistor elements carried by saidbars in the form of flat depending coils; with auxiliary barsrespectively mounted loosely in the bottoms of said coils.

9. The combination in an electric furnace of a casing; series of columnsections doweled together; horizontal cross bars carried by adjacentcolumns; and resistor elements hung from said cross bars.

10. The combination in an electric furnace of a casing; columns mountedtherein and each consisting of a series of sections connected by dowels;fittings interposed between the sections of the columns; horizontal barscarried by the fittings; and resistors hung respectively from said bars.

11. The combination in an electric furnace of a casing; verticallyextending columns mounted adjacent the sides of the casing; horizontalbars supported by said columns; vertically set resistor coils carried bysaid bars and resistor elements extending substantially parallel withand immediately adjacent the floor of the casing.

12. The combination in an electric furnace of a casing; verticallyextending columns adjacent the side walls thereof; supporting memberscarried by said columns and extending adjacent the top of the casing;horizontal bars carried 'by said members; other horizontal bars carriedby the columns; vertically extending resistor coils carried on saidlatter bars adjacent the sides of the casing; and other resistorelements supported on the bars carried by the top members.

13. The combination in an electric furnace of a casing; a series ofcolumns supported solely by the floor of said casing. and eachconsisting of a series of separably connected sections; cross fittingsinterposed between the sections of said columns and each having at leastone upwardly opening recess; horizontal bars removably carried in therecesses of adjacent fittings; coils hung from said bars respectively;and means for spac-- ing the lower parts of said coils.

14. The combination in an electric furnace of a casing; a series ofcolumns supported solely by the floor of said casing and each consistingof a series of separably connected sections; cross fittings interposedbetween the sections of said columns and each having at least oneupwardly opening recess; horizontal bars removably carried in therecesses of adjacent fittings; coils hung from said bars respectively;and means for spacing the lower parts of said coils consisting ofauxiliary bars loosely hung therein. v

15. The combination in an electric furnace of a'casing; a frame withinthe casing carried solely by the floor thereof independently of the sidewalls, said frame comprising a plurality of sets of built-up columns andremovably positioned connecting bars individual to each set; andresistor elements mounted on said removably positioned connecting bars.

THEODORE B. BE CHTEL.

